#include <bits/stdc++.h>
using namespace std;
double Dis(int ,int ,int ,int );
int main(){
	int x1,y1,x2,y2,x3,y3;
	cin>>x1>>y1>>x2>>y2>>x3>>y3;
	double sum = 0.00;
	sum += Dis(x1,y1,x2,y2);
	sum += Dis(x1,y1,x3,y3);
	sum += Dis(x3,y3,x2,y2);
	printf("%0.2f\n",sum);
	return 0;
}
double Dis(int x1,int y1,int x2,int y2){
	double result;
	result = sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));	
	return result;	
}
